1. Field of the Invention
This invention relates to an apparatus that mixes fine particles with flowing liquid to form either a slurry or a solution, and more particularly to an apparatus that injects fine powders into a high pressure liquid stream.
2. State of the Prior Art
Fine hygroscopic powders, when mixed with a liquid, tend to agglomerate before they are either completely mixed or dissolved. To avoid these agglomerations, the powder should be finely sprinkled onto the liquid and mixed thereafter.
Apparatus for dissolving hygroscopic powders into liquids are well known. One such apparatus is disclosed in the Burford U.S. Pat. 3,207,365. In the Burford apparatus, hygroscopic powder is fed from a hopper into a feed screw which advances the powder over an opening in the feed screw encasement thereby letting the powder freely fall. The dispensed powder falls into a conical dissolving chamber and is washed down by a spray of water is tangential to the conical dissolving chamber. The water-powder mixture passes through the vortex of the conical dissolving chamber and into an ejector. Another stream of liquid flows under pressure through a nozzle in the throat of the ejector to dissolve most of the hygroscopic powder. This solution is then piped into a working solution tank.
In the U.S. Pat. No. to Pfeuffer, 3,039,655, infusorial earth filter material or the like is charged into a liquid that flows in a pipe with variable pressure. The filter particles are dispersed by an air stream which is introduced tangentially into a bin. The filter particles flow through a valve and into a mixing chamber through which flows liquid to carry the filter particles in the main pipe. In another embodiment of the Pfeuffer device, in addition to the air stream, the liquid enters the bin in a spray form to mix with the earth particles falling therethrough. The spray can either come from a single nozzle or a pipe with many fine apertures surrounding the bin.
The motorized screw device used by Burford and the air flow device of Pfeuffer may be adequate for injecting small or moderate amounts of powder at a slow rate into a liquid but are inadequate for injecting extremely hygroscopic powders at a fast rate. The feed screw mechanism in the Burford device will not disperse the powder adequately to avoid agglomeration on the conical dissolving chamber. The Pfeuffer air chamber will not disperse hygroscopic powder at rapid rates without some agglomeration. These two devices and others are believed to be incapable of injecting substantial amounts of hygroscopic powders in a short period of time into a liquid without agglomeration.